The present invention relates generally to an electrical contactor for conducting electrical signals between a chip being tested and a printed circuit board for testing chips.
Currently available electrical contactors that interface chips and printed circuit boards that test the chips typically use conductive wires or spheres to conduct electrical signals between the chip and the printed circuit board and to ground the chip on the printed circuit board. Although these wires and spheres may be adequate for conducting electrical signals, they often do not do a good job of grounding the chip under test, especially grounding radio frequency (RF) signals.
Additionally, currently available electrical contactors typically use plastic guide frames that require screws for mounting. The plastic guide frames reduce accessibility to the printed circuit board, making tuning of the electronic components on the printed circuit board difficult. Furthermore, mounting and dismounting electrical contactors having plastic frames and screws is time consuming.
Currently available electrical contactors also typically have large profiles that can electrically interfere with sensitive electronic components contained in the chip and, therefore, can affect the results of chip testing.
There is a need, therefore, for an electrical contactor that can establish a good direct current ground as well as an RF signal ground, does not require a frame that can decrease accessibility to the printed circuit board, mounts and dismounts easily and quickly from the printed circuit board, and has a thin profile to avoid electrically interfering with electronics contained in the chip.
In accordance with a preferred embodiment of the present invention, the foregoing and other objects and advantages are attained by an electrical contactor for establishing electrical contact between a chip and a printed circuit board for testing chips comprising at least one interconnect that electrically connects at least one chip lead to the printed circuit board and a separate ground contact that grounds the chip through a ground located on the bottom of the chip. The ground contact preferably comprises a block of metal that contacts is shaped to fit in an indentation in a ground layer located beneath the printed circuit board. In addition, the ground contact may further comprise solder applied on top of the block of metal for establishing a good contact with the ground on the chip. Moreover, the ground contact preferably also functions as a solid stop to prevent a chip being plunged on the electrical contactor during testing from damaging the electrical contactor.
The electrical contactor preferably further comprises an interposer, wherein at least one interconnect is fabricated on the interposer. The at least one interconnect preferably comprises an abrasive material that scratches open the surface of a chip lead, exposing conductive material to establish good electrical contact.
The electrical contactor preferably further comprises a conductive elastomer bonded to and below the interposer. The conductive elastomer preferably comprises an array of wires embedded in an elastomer wherein the wires carry electrical signals between the at least one interconnect and the printed circuit board. The elastomer absorbs the compressional forces imparted when the chip is plunged on the electrical contactor, thus protecting the printed circuit board. Preferably, the wires are parallel to one another and oriented at a slanted angle.
The bonded interposer and conductive elastomer preferably contain at least one hole for mounting the contactor on at least one dowel on the printed circuit board. An O-ring preferably secures the bonded interposer and conductive elastomer layer to the at least one dowel on the printed circuit board. In addition, the bonded interposer and conductive elastomer preferably have a thin profile to avoid electrically interfering with electronic components contained within the chip being tested.